Vapor electric device



Jan, 31, 1933; w. G. MORAN VAPOR ELECTRIC DEVICE Filed May 51, 1930 INVENTOR ATTORNEY iatented Jan. 31, 1933 UNITED STATES PATENT OFFICE WILLIAM GBEGOB MORAN,

HOUSE LAMP COMPANY,

VAPOR ELECTRIC DEVICE Application filed Kay 31, 1980. Serial No. 468,845.

This invenion relates to electric discharge devices and more particularly to vapor electric devices of the mercury rectifier type employing incandescent thermionically actlve cathodes.

One of the objects of the present invention is to provide a hot cathode mercury recti fier which will operate efiiciently over a wide range of external ambient temperatures.

Another object of this invention is to provide a hot cathode mercury vapor rectifier device which will operate in any position or attitude with respect to gravity.

Another object of this invention is to provide an improved type of hot cathode mercury vapor rectifier which will efiiciently rectify both halves of an alternating current cycle within a single tube, over a wide range of ambient temperatures and substantially independently of the position thereof with res ectto gravity.

other object of this invention is to provide means in the hot cathode mercury vapor rectifier for restraining the How of the excess mercury thereof when the device is subjected to displacements in mounted position.

These and other objects and advantages will become apparent as the invention is more fully disclosed.

In accordance with the objects of my invention I have provided a novel type of hot cathode mercury vapor rectifier within which the mercury of the device is present, at least in part, as an amalgam deposited about the walls of the enclosing envelope, and Within which is provided means for efiecting the vaporization of the mercury from the amalam. g In the preferred form of the present invention, I incorporate within a tubular shaped envelope two anodes and one thermionically active hot cathode, the anodes being electrically connected to the cathode by means of an external electric circuit so that each half of the phase of an alternating current cycle impressed thereon is rectified. The mercury is superficially amalgamated with a film of metal integral with the enclosing glass-envelo e and the cathode is positioned adjacent the 1m so as to effect a ready vaporization of the mercury upon incandescence. The amalgamated metal film, however, should be positioned within the device so as to be located substantially in the coolest portion of the device when the device is being operated.

Before further disclosing the invention reference should be made to the accompanying drawing wherein,

Fig. 1 discloses in side elevational view partly 1n section one form of a hot cathode mercury vapor rectifier constructed in accordance with the present invention;

Fig. 2 discloses in side elevational view partly in section a second modification of the same; V

Fig. 3 is a plan view taken along plane IIIIII in Fig. 1 of the type of hot cathode preferably employed therein;

Fig. 4 is a view taken along plane IV-IV Fig. 1, showing one type of anode employed; an

Fig. 5 is a view taken along plane V-V in Fig. 2 showing a second type of anode employed.

Referring to Fig. 1 the full wave hot cathode mercury vapor rectifier disclosed therein comprises an enclosing tubular envelope 1, a cathode 2 extending therein at one end, and two anode electrodes 3 and 4 separately sealed in the other end and separated from each other by baflle or other suitable arrangements such as tubulatures 5 and 6. The entire device being mounted at its cathode end in a base member 7 the cathode lead wires 8 and 9 extendin through seal 10 into base pin contact mem ers 11 and 12. The device may be exhausted through a tubulature extending throu h the stem of the cathode seal as indicated at 13.

Inaccordance with the present invention cathode 2 is comprised of a crimped sheet or strip filament exteriorly coated with thermionically active material. The strip filament may be comprised of nickel, platinum, or other suitable alloy such as silicon nickel. The exterior coating preferably comprises a mixture ofalkaline earth metal oxides. The crimped strip filament is mounted so as to present the edges thereof perpendicularly to the plane surface of the anode electrode.

cathode in such position that the same is This reduces the electrostatic strain thereon.

While it is preferable to employ an oxide coated type filament because of its greater thermionic activity at relatively low temper atures, other type thermionical y active cathodes such as pure tungsten, thoriated tungsten, and equivalent types of such cathodes may be employed, if desired. The cathode 2, if desired, may be of the indirectly heated type, and may also be coil shaped or filamentary in shape. The anodes are comprised of carbon, graphite, or any highly refractory metal with or without an exterior coating of oxide.

The enclosing glass envelope is preferably tubular in shape, such as is shown in the drawing, andof an inside diameter such that the heat radiated from the incandescent cathode is readily absorbed therein. However, it is not to be construed that.I am limited to the tubular shaped envelope, nor to the specific positioning of the electrodes therein, such as is set forth in the drawing. For example, with extremelyhigh voltages, it may be desirable to have the anode electrodes extending at right angles to the oathode from opposite sides of the enclosing envelope, and the envelope may be globular, spherical, spheroidal or other such shape, if desired. It is essential, however, to the practice of the present invention to incorporate the mercury within the device at least in part as an amalgam and to provide means therein for effecting the vaporization of the mercury.

It is contemplated, for example, that the mercury amalgam may be heated by an auxiliary heater element operating in conjunction with or separately from the cathode, where a spherical or other shaped enclosing glass envelope is employed, or where the distance between the anodes and the cathode in the tubular envelope is excessive.

In the practice of the present invention in constructing a device in accordance with the preferred embodiment thereof, the envelope is exhausted in the usual manner after assemblin the electrode elements therein and a-few rops of mercury introduced within the device either before or subsequent to the usual exhaust and degasification process.

This mercury is converted at least in part into an amalgam integral with the. wall of the enclosing glass envelope by effecting a distillation of a. metal film upon the walls of the enclosing glass envelope, subsequent to exhaust which film is comprised of a metal such as magnesium, calcium, aluminum, barium and the like which will amalgamate with the mercury at least superficially.

1 Thereafter the mercury is amalgamated therewith, in any desirable manner. The deposition of the film is preferably effected upon a portion of the envelope adjacent the heated upon an incandescing of the cathode.

The distillation of the metal vapor film on to the enclosing envelope is accomplished in the usual manner by providing a tab 14 upon which is positioned a stri or piece 15 of the metal to be vaporized. ubsequent to exhaust and sealing off, the tab is heated to elevated temperatures, as by high frequency induction, in a manner well known in the art, to effect the va orization of the strip or piece 15. The deposited metal vapor being highly reactive and substantially free from surface films of impurities readily wets with the mercury to form at least superficially an amal- There still remains, however, a pressure of mercury vapor in the device. Upon an incandescence of the cathode this vapor pressure will become increased depending upon the number of watts heat energy liberated therein, the relative close spacing of cathode to the envelope walls and upon the particular thermal stability of the amalgam.

For the purposes of the present invention I have found that magnesium is the preferable metal to employ for the amalgamating with the mercury, as the magnesium-mercury amalgam appears to have a suitably high vapor pressure in vacuo for the purposes of the present invention over relatively large ambient temperature ranges, and moreover may be readily decomposed by heating to elevated temperatures, reforming upon cooling. It is important in this respect to locate the magnesium metal film upon a portion of the enclosing glass envelope which v 1] 1e relatively the coldest portion thereof curing operation of the device to avoid loss of the same by vaporization.

The design of the device shown in Figs. 1 and 2 and the constituent materials and relative position of the various parts therein are such that the device will operate over a wide range of ambient temperaturestorectify alternating current voltages of several thousand volts. It has been tested under loads where the peak inverse voltage is eight thousand volts or more. The device will start and continue to operate without auxiliary heating apparatus at temperatures ranging from lower than 20 C. to higher than C. This is due to the compactness of the desi n and to the relative positioning of the e ements therein, which are such that all parts of the device reach operating temperatures from any one of a wide range of ambient temperatures within a relatively few seconds of the lighting of the filament.

The device shown in Figs. 1 and 2 isof the full wave rectifying type and is capable of rectifying both halves of an alternating current cycle within the single device. It is not possible to do this with any other form of hot cathode mercury vapor rectifier heretofore devised. The electric circuit utilizing the same has not been graphically set out in the drawing as the circuit itself is old and well known in the art.

One of the specific advantages that is obtained by the practice of the present invention is that the mercury is restrained from flowing about the interior of the device by reason of its amalgamation with the vaporized film of metal upon the glass walls of the envelope. This ermits operationof the device in practice y any position or attitude with respect to gravity, without risk of damage or of failure to operate, while in such attitudes. This feature, so far as is known, is not found in any hot cathode mercury vapor rectifier now known. All previous tubes have been expressly and definitely limited to certain stated attitudes or operating positions relative to the direction of gravity. Whereas Ihave indicated in the drawing that the mercury is present in the device as an amalgam integral with the enclosing glass envelope, it is apparent that the mercury may be present as an amalgam upon the surface of a metal foil or strip member positioned with respect to the cathode, in such manner as to be heated by the cathode. Such positioning of the metal foil or strip member, as in the location of the amalgam upon the lass envelope, however, must be such that uring operation of the device the amalgam is relatively cold as compared to the rest of the tube so as to prevent total loss of the amalgam therefrom by distillation.

The device shown in Fig. 2 is essentially no different from that set forth in Fig. 1,

'closin glass envelope containing a thermlonica y active cathode, one cooperating electrode, a metal fihn depositedv on a part only of said envelope remote from said cooperating electrode and amallgamated with mercury, said mercury ama gam being adjacent said cathode for readily vaporizing the mercury therefrom upon initial cathode heating, said-location of said mercury amalgam being at a relatively cool portion of the device, when said device has been in operation over a substantial period of time.

In testimony whereof, I have hereunto subscribed my name this 26th day of May,

WILLIAM GREGOR MORAN.

be many modifications and deexcept for the anode structure which'is flat surfaced rather than spherical as'heretofore is customarily emplo ed. For some purposes the flat surface electrodes are preferable to the spherical because of the greater heat radiating qualitiesof the former, thereby rmitting higher voltages to be applied 1: ereto.

In addition to being a very useful tube for ordinary rectifier purposes in radio and non-radio installations, the special features make this tube suitable for the rectifyin of alternating current voltages under specia conditions or circumstances. It is particularly advantageous as a rectifier for aircraftor other radio or non-radio apparatus where the operating conditions include a wide range of ambient temperatures, the presence or absence of. vibration, sudden orientations with respect to the line of motion, and any relative position whatsoever with respect to the direction of gravity. Under such condi- 

